Atmospheric circulation and storm events in the Baltic Sea

Abstract

The storm events in the Baltic Sea are examined in connection with the main weather patterns grouped into the circulation types (CTs), and their changes in present climate. A calendar of storms was derived from results of wave model SWAN (Simulating WAves Nearshore) experiments for 1948-2011. Based on this calendar, a catalogue of atmospheric sea level pressure (SLP) fields was prepared for CTs from the NCEP/NCAR dataset. SLP fields were then analyzed using a pattern recognition algorithm which employed empirical orthogonal decomposition and cluster analysis. For every CT we conducted an analysis of their seasonal and interannual changes, along with their role in storm event formation. An increase of the storm CTs’ frequency in the second part of the 20th century was shown to be in a close agreement with teleconnection circulation patterns such as the Arctic Oscillation, North Atlantic Oscillation and the Scandinavian blocking.

Keywords

• atmospheric circulation
• storm events
• classification